429
FXUS66 KEKA 302008
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1240 PM PDT Wed Jul 30 2025

.SYNOPSIS...Chance of thunderstorms is forecast for the interior
of Northwest California through Friday. Storms may produce strong
and gusty outflow winds, heavy rain and hail.

&&

.DISCUSSION...

Scattered to numerous thunderstorms are forecast to fire up over
Trinity County and eastern portions of Humboldt and Del Norte this
afternoon and evening. Storms will likely produce a combination
of heavy rain, gusty outflow winds and perhaps near 1" hail. Chances
for storms are highest in Trinity (45-55%) and much less for eastern
Del Norte and eastern Humboldt (15-25%). Strikes on dry fuel beds
away from the precip cores and swift N-NW storm motions, may still
result in numerous fire starts. Now, individual CAMS continue to
indicate isolated precip cores with 0.50in/hr over Trinity County.
Soundings also continue to indicate inverted-V profiles and
potential for micro-bursts with outflow gusts to 30-50 mph.

The mostly wet thunderstorm activity is forecast to continue on
Thursday, with a more northward and eastward shift in the axis of
storm activity. Once again greatest chances will be over Trinity
with lower chances along the periphery of NE Humboldt and eastern
Del Norte. Confidence on the areal coverage for Trinity is low and
for now will hold off on hoisting another fire weather watch for
abundant lightning.

Friday will also feature another round of thunderstorms, confined
to mostly the northern Trinity mountains. Potential for thunderstorms
should decrease on Saturday as 500mb heights build and drier
westerly flow spreads across the area. A shorter wavelength
trough will approach on Sunday bringing yet another round of
possible showers and interior thunderstorms. Otherwise, temps will
remain near seasonal averages through the weekend. Incoming
trough on Sunday will likely induce stronger westerly to northwest
winds for our typically dry and windy areas; Lake, southern
Mendocino and eastern Trinity. These enhanced breezes may last
into Monday.

Interior temperatures will likely begin to warm up by mid next
week. How warm remains uncertain. 500mb heights pump up to 588DM
or more and suspect some of the more typical valley hot spots will
reach or exceed 100F. Models continue to show upstream troughs in
westerly flow busting down the ridge. These upstream troughs may
mitigate the threat for another long duration heat wave.

&&

.AVIATION...

18Z TAFs...Broad upper troughing with embedded shortwave disturbances
are maintaining a deep marine layer. This will continue to greatly
reduce the chances for LIFR ceilings and fog (visibility of 1/2SM
or less). Scattered interior thunderstorms are forecast this afternoon,
mainly in Trinity County. Storm downdrafts may produce strong
outflow wind gusts with micro-bursts. Severe to extreme turbulence
are forecast in and around storms. Southerly wind reversal eddies
will develop Wednesday and will further add to more diurnally
persistent stratus. Soundings show further deepening likely under
this continued pattern and this will keep the stratus more
persistent, but a period of scattering is possible.

&&

.MARINE...

Winds are forecast to trend upward today, with gusts up to 25-30
kts in the outer waters and gusts to 15-20 kts possible nearshore.
Wind driven seas of 5-7 ft are forecast for the outer waters
today, with slightly higher and steeper waves found south of Cape
Mendocino. Steep wind waves south of the Cape may propagate
nearshore, with seas rising to 6-7 ft tonight. A similar pattern
is expected Thu through Fri, with the potential for slightly
higher winds into the weekend. Localized gales force gusts are
likely downwind of Cape Mendocino.

&&

.FIRE WEATHER...A red flag warning for abundant lightning remains
in effect for zones 283 and 204 through this evening. Storms will
likely produce a combination of heavy rain, gusty outflow winds
and perhaps near 1" hail. Strikes on dry fuel beds away from the
precip cores may still result in numerous fire starts. The mostly
wet thunderstorm activity is forecast to continue on Thursday,
with a more northward and eastward shift. Once again greatest
chances will be over the Shasta-T in zone 283 and perhaps along
the periphery of NE Humboldt and eastern Del Norte. Confidence on
the areal coverage is low and for now will hold off on hoisting
another fire weather watch for lightning. Friday will also feature
another round of thunderstorms, confined to mostly the northern
Trinity mountains. Potential for thunderstorms should decrease on
Saturday as 500mb heights build and drier westerly flow spread
across the area. A shorter wavelength trough will approach on
Sunday or Sunday night bringing yet another round of possible
showers and interior thunderstorms. Otherwise, temps will remain
near seasonal averages through the weekend. Incoming trough on
Sunday will likely induce stronger westerly to northwest winds for
our typically dry and windy areas; Lake, southern Mendocino and
eastern Trinity.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Red Flag Warning until 11 PM PDT this evening for CAZ204-
     283.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 PM this afternoon to 3 PM PDT
     Thursday for PZZ455.

     Small Craft Advisory until 3 AM PDT Thursday for PZZ470.

     Small Craft Advisory until 3 PM PDT Thursday for PZZ475.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png